In a fluid machine that has stator vanes and rotor vanes such as a turbine or compressor, there are cases of applying a variable stator vane whose angle can be adjusted in order to adjust the output. Such a variable stator vane is mounted to the inner circumferential surface side of a casing so as to be rotatable about its center axis. At the base end of the variable stator vane, a rotation shaft extends toward the outer circumferential side so as to be coaxial with the center axis of the variable stator vane, and the rotation shaft projects to the outer circumferential side of the casing. Then, a lever is mounted to the distal end portion of the rotation shaft that is projected to the outer circumferential side of the casing, and by turning the lever with a driving apparatus that is mounted to the outer portion of the casing, the angle of the variable stator vane is adjusted, and the variable stator vane is maintained at the adjusted angle.
Here, the angle of the variable stator vane is adjusted by the rotation angle of the lever as described above. For that reason, the lever must be accurately mounted so as to attain a predetermined angle with respect to the variable stator vane and the rotation shaft, and it must be firmly mounted and resist the torque that acts by the pressure that the variable stator vane receives from the fluid that flows around the variable stator vane during operation. Conventionally, the mounting structure 100 as shown in FIG. 16 and FIG. 17 has been adopted for the mounting structure of the rotation shaft and the lever. That is, these drawings disclose a structure in which fitting holes that are in communication are formed in the rotation shaft 90 and the lever 91 that the rotation shaft 90 in which the rotation shaft 90 is fitted, and a key 103 that in cross section has a C shape is press fitted into the fitting holes 101 and 102 that are in communication, while causing the cross-sectional shape to resiliently deform. In such a structure, by inserting the aforementioned key 103 into the fitting holes 101 and 102, the mutual fitting holes 101 and 102 are fixed in an aligned state, and thereby the lever 91 is fixed at a predetermined angle with respect to the rotation shaft 90. Also, they are firmly fixed to each other by the key 103 being press fitted while resiliently deforming its cross-sectional shape.
Also, as a different type of mounting structure, there is known one that provides a tapered protrusion on the rotation shaft, and forms on the other side a tapered groove in a manner allowing insertion of the protrusion, and by tightening both by a tightening mechanism that is provided on the rotation shaft, presses the protrusion and the tapered groove against each other (for example, refer to patent Documents 1 and 2).